How important is EMI and RFI rejection?

Thanks for the AA link. I see he's basically saying he prefers a floating ground vs actual ground. I'd say that's fine - most of the time. The goal of good ground design is to get all the equipment at the same negative voltage level. For actual ground this is 0 volts. In a floating ground it can be... well anything really but usually a few millivolts. The main thing is that everything is at the same voltage level. The "usually OK" part is if you really do have EMI/RFI problems. This is because the other goal of good grounding is to shunt excess energy away from the system. In a floating system, there is no where for the excess energy to go. This can still be fixed with a five cent capacitor.

Booboobaer, no one has said well designed cables that shunt EMI/RFI to ground don't make a difference. Or that grounding isn't important. Or that you can't hear a difference. To the contrary, it is all extremely important. It just isn't expensive.

This is because the other goal of good grounding is to shunt excess energy away from the system. In a floating system, there is no where for the excess energy to go. This can still be fixed with a five cent capacitor.
Danmyers (System | Answers)

Danmyers, how would you fix it with a five cent capacitor?

Hi Clio,

Assuming RFI is the issue a .01uF ceramic bypass capacitor connected between the floating ground and real ground will shunt all the radio frequency energy away from the audio system and to real ground.

Dan

Or, one could lift the ground from the component chassis (has to be 3 inches from the IEC socket to conform to UL codes), and ground back to the original earth ground (where all the components plug into so you have 1 ground to meet UL codes), via a wire configuration. I have begun this process with good results-after 40 years in this hobby I am learning just how critical it is to properly ground your system.

Powder, I'd be interested in learning more. Feel free to email me offline to describe what you are doing.

I have a couple of components where the manufacturer does not have the ground connected at the IEC inside the components. Says it is a huge source of noise. Not sure how the grounding was addressed if at all. Never had any shocks and it sounded great.